| PMSMs have been widely used in electrical vehicles due to its high power density,high efficiency and wide operation speed range.Since better NVH performance of electric vehicles are desired by consumers nowadays,noise and vibration induced by electromagnetic excitations has attracted many research interests due to its complexity and importance.Aiming at exploring the mechanism and the characteristics of electromagnetic vibration,a series of related topics including characteristics of the electromagnetic excitation,modeling methods,multi-physics analysis and factors influencing the electromagnetic vibration are comprehensively discussed in this paper.Firstly,both numerical calculation and analytical derivation regarding the harmonics of magnetic fluex density and eletctromagnetic force are conducted and both of which proves to be effective in prediction the composition of harmonics.Harmonic analysis is useful for identifying the cause of electromagnetic vibration and noise therefore it is essential for NVH optimization.The paper then studied the accurate prediction of modal parameters of motor stator considering the effect of laminated stator core and distributed windings.Finite element modal analysis results are compared with the modal test result to verify the effectiveness of the modeling method and the analytically method to calculate material parameters.Finally,the characteristics of electromagnetic vibration considering factors like circumferential mode of force,motor operation points,rotor eccentricity,rotor skewing,slot pole combination and etc.are explored and studied.The current harmonics introduced by power inverter are also studied.The force harmonics and resulted vibration considering the effect of all the aforementioned factors are examined and characterized.Conclusions made in this section help to minimize the error of numerically predicted response and laid solid foundation for future NVH optimization. |
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